so i got a code for the TPS so i decided to clean the throttle body before i bought a new one for $400. I also changed the plugs while i was working on it but here are the before and after pics. it wouldnt be a bad idea for some of you guys to do this also if your able to.

just cleaned mine also, looked just like yours. i did a huge job over the weekend: valve cover gasket, oil filter housing gasket, spark plugs, micro filter, air filter, it was good work.
I wonder how the throttle body gets that oil all over it?

Where is that film/oil coming from? Is that a problem long term and are there any fixes for it?

I haven't spent too much time under the hood of an e90, but I'd guess it could be EGR (exhaust gas recirculation) or PCV gasses. Both would be normal.

EGR systems take some exhaust gas and inject it into the inake air stream under certain conditions to reduce emissions. It contains carbon deposits that would build up over time.

PCV is positive crankcase ventilation. It releases pressure from the crankase. Instead of venting the air into the atmosphere, it injects it into the intake stream. This air also has unburned fuel and oil.

EGR is probably the best explanation. My other guess is just from exhaust gasses from other cars that pass by the filter and stick to the throttle plate because the intake manifold after the TB was clean

Thanks for sharing the pics and insights on the cause of the buildups!

I don't want to derail, but are you using a torque wrench when doing all of this work? If so, a fancy one, or a Harbor Freight/Sears one? I'd love to do some of this DIY stuff, but know that proper tools are a necessity, and I wonder how you other weekend warriors are equipped. I know there is a lot of debate about these, but would like to do work like this and other things on my CPO car, so want to have a perspective of how you do it.

EGR is probably the best explanation. My other guess is just from exhaust gasses from other cars that pass by the filter and stick to the throttle plate because the intake manifold after the TB was clean

Did you take any pics of the intake arm? I ask because there was a fluid of some kind in mine I noticed when changing air filters recently. See pics below.

I haven't spent too much time under the hood of an e90, but I'd guess it could be EGR (exhaust gas recirculation) or PCV gasses. Both would be normal.

EGR systems take some exhaust gas and inject it into the inake air stream under certain conditions to reduce emissions. It contains carbon deposits that would build up over time.

PCV is positive crankcase ventilation. It releases pressure from the crankase. Instead of venting the air into the atmosphere, it injects it into the intake stream. This air also has unburned fuel and oil.

That's what it is on most engines, btw that picture in the OP does not look that bad.

re; cleaning intake
what about a drip line that could be inserted into the air stream (past the MAF) to clean the intake
the question that i have is;
what does the throttle plate and associated system look like for E90.?
i cant think of anything what would be a problem:dunno:

Gonna clean mine this weekend also when doing spark plugs. Any tips or special tools needed or just remove intake and unbolt the TB. What did you use to clean it? Notice anything better about how the car feels after cleaning?